Abstract
The Processing-body is a conserved membraneless organelle that has been implicated in the storage and/or decay of mRNAs. Although Processing-bodies have been shown to be induced by a variety of conditions, the mechanisms controlling their assembly and their precise physiological roles in eukaryotic cells are still being worked out. In this study, we find that a distinct subtype of Processing-body is induced in response to conditions that disrupt microtubule integrity in the budding yeast, Saccharomyces cerevisiae. For example, treatment with the microtubule-destabilizing agent, benomyl, led to the induction of these novel ribonucleoprotein granules. A link to microtubules had been noted previously and the observations here extend our understanding by demonstrating that the induced foci differ from traditional P-bodies in a number of significant ways. These include differences in overall granule morphology, protein composition, and the manner in which their induction is regulated. Of particular note, several key Processing-body constituents are absent from these benomyl-induced granules, including the Pat1 protein that is normally required for efficient Processing-body assembly. However, these novel ribonucleoprotein structures still contain many known Processing-body proteins and exhibit similar hallmarks of a liquid-like compartment. In all, the data suggest that the disruption of microtubule integrity leads to the formation of a novel type of Processing-body granule that may have distinct biological activities in the cell. Future work will aim to identify the biological activities of these benomyl-induced granules and to determine, in turn, whether these Processing-body-like granules have any role in the regulation of microtubule dynamics.